Formation of interchain disulfide bonds and helical structure during biosynthesis of procollagen by embryonic tendon cells.
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Interchain disulfide bonding in the procollagen synthesized by tendon cells from chick embryos was examined by gel filtration and polyacrylamide gel electrophoresis of reduced and nonreduced forms of the proteins in dodecyl sulfate. The results indicated that the major part of both the newly synthesized intracellular procollagen and the secreted procollagen consisted of pro- chains linked by disulfide bonds. In addition to procollagen in which the three pro- chains were linked by disulfide bonds the medium from the cells also contained smaller amounts of procollagen-like protein in which the collagen portion was still triple helical but the interchain disulfide bonds were missing. The observations suggested that the conversion of procollagen to collagen can occur by several discrete steps, the first of which may remove regions close to the NH2-terminal ends containing the interchain bonds. Experiments in which the cells were pulse labeled for 4 min with [14C]proline and then the label chased demonstrated that at the end of the pulse-labeling period prochains were recovered which did not have interchain bonds and which were not helical as tested by limited proteolytic digestion. Interchain bonds and triple-helical structure appeared in the molecule at about the same time, and a chase period greater than the synthesis time for pro- chains was required to obtain maximal values for interchain bonds and helical structure. In further experiments the cells were incubated with the iron chelator,-dipyridyl so that prolyl and lysyl hydroxylases were inhibited. The intracellular pro-chains were linked by disulfide bonds even though the absence of hydroxyproline in the polypeptides prevented them from becoming triple helical at 37. The results suggested that formation of interchain disulfide bonds may play an important role in the formation of the helical structure of collagen. 1974, American Chemical Society. All rights reserved.
author list (cited authors)
Schofield, J. D., Uitto, J., & Prockop, D. J.
complete list of authors
Schofield, JD||Uitto, J||Prockop, DJ